It is commonplace today for industrial and commercial electric consumers to install energy management systems to record and analyze their electrical usage. At minimum, these systems allow the consumer to collect data over time related to the businesses power consumption which can later be analyzed in order to make adjustments to the facility to maximize power consumption efficiency and reduce power costs.
Energy management systems may include a demand controller to optimize the energy usage of a particular consumer, such as a factory, hotel, retail establishment, entertainment facility, or warehouse. A demand controller measures over time the power consumed by a business, and adjusts xe2x80x9crun timesxe2x80x9d for short durations on certain electrical devices when the power load is too high by taking electrical equipment off-line. A demand controller is configured by consumer settings which includes a permissible maximum peak demand and a priority and order in which the controlled devices are to be turned off.
When the power consumption returns to an acceptable level, the demand controller will automatically allow the off-line equipment to turn back on. A demand controller typically uses complex mathematical formulae, sometimes performed on a realtime basis, with models of power usage built over time, to provide for the lowest peak demand charge.
For input regarding current energy usage, energy management systems typically collect three channels of energy related pulses from the consumer""s electric meter. Usually, the electric meter is the meter installed by and owned by the electric utility company, and thus the consumer may have little or no choice in the model installed.
These usage pulses, commonly referred to as xe2x80x9cKYxe2x80x9d or xe2x80x9cKYZxe2x80x9d pulses, are created by relay contacts within the meter. The relay contacts are operated by the meter to create pulses by alternately opening and closing the relays at a rate relative to the electrical usage at any given time. The summation of usage pulses over one hour could be the measurement of kilowatt-hours, in one instance. Other channels could be kilovar-hours (reactive energy), or others, in other configurations or other instances.
An end-of-interval (xe2x80x9cEOIxe2x80x9d) pulse is also created, as well, in many cases, which allows the energy management system to synchronize its time period to that of the meter.
In the simplest method, these pulses are collected via cabling from the electric meter to the energy management system equipment. This is a practical solution when the electric meter is relatively close to the energy management system. However, in some applications, especially commercial facilities such as large grocery stores and home improvement centers, the meter is located with the pad mount distribution transformer across a back service parking lot, usually within 100 feet of the rear of the building. Installation of cabling from the building to the remote meter can often be a challenge, requiring digging up the parking lot to bury the 100 feet of cable from the meter location to the energy management system location. Alternatively, installing overhead wires in such an area which is usually heavily traveled by trucks to the rear side of a facility can be expensive and prone to damage.
Automatic Meter Reading (xe2x80x9cAMRxe2x80x9d) is also well-known in the art. AMR consists of technologies and methods to remotely read a plurality of electric meters, such as a consumer base for an electric supplier company, into a billing database. Often times, these systems are designed for and intended for data collection by a service vehicle passing by the consumer""s facility, or by a fixed data transmission means. For example, some AMR units consist of a collection unit attached to the consumer""s electric meter, and a mobile receiver mounted in a service vehicle. As the vehicle passes near the electric meter, the receiver emits a signal to the collection unit, which causes the collection unit to transmit send its meter reading data to the receiver. This consumption data is then stored and later entered into a billing system. Another common type of AMR system uses a dial-up modem in the collection unit to dial a remote billing system and transmit its reading data via telephone lines. Still other variations of this theme include using data channels in wireless telephone systems to transmit usage data to a remote billing system via a wireless telephone network, such as PCS or cellular.
With currently available AMR systems, the wireless communications network not only is the data transport means, but also concentrates data from all electric meters on the network for a single feed to the utility billing computer. The KY, KYZ and EOI pulses from the originating meters are merely a universal means of transferring information from the meter to the AMR collection unit adjacent to the meter. But, the count or states of the pulses and relays are not actually transmitted to the billing system. As such, the consumption data from AMR collection units are usually in proprietary formats, and can only be received and decoded by a specific billing system.
Thus, the existing AMR remote meter reading systems are not suitable for use in transmitting meter relay states from the back of a facility pad to the energy management system owned by the consumer inside the consumer""s facility. On the one hand, an AMR collection unit outputs are not compatible with the required KY, KYZ and EOI pulse inputs to typical energy management systems. On the other hand, even if the outputs of the AMR collection unit were compatible with the inputs of the energy management system, traditional AMR systems are not cost-effective for such an application whereas they are designed to distribute the costs of the AMR system of a large population of power consumers, not to be borne by a individual consumer.
Therefor, there is a need in the art for a system to communicate electric meter relay states and pulses from a first location of an electric meter to a second location of an energy management system. This system should be compatible with common KY, KYZ and EOI relay outputs of electric meters, and KY, KYZ and EOI relay inputs to energy management systems. Further this system should faithfully reproduce the states of the relays and pulses using an isolation technology which is reliable and error-free in order to allow for efficient management of the consumer""s electric loads based on the usage data collected from the meter. Optimally, the system should use an isolation technology which is commonly available and is license-free.
The wireless isolation relay consists of two units: a meter unit and a building unit. The meter unit is co-located adjacent to the electric meter, and the building unit is mounted inside the consumer""s building near a consumer""s energy management system. The two units are interconnected using a wireless, license-free means such as RF (radio frequency). Meter relay pulses are input to the meter unit from the co-located meter, and relay states or counts are transmitted to the building unit system where the states of the relays (and pulses) are faithfully regenerated as outputs to the energy management system. The pulses output from the building unit perform as though they were created by the meter originally, but without the necessary wired connection. The circuitry of the transmitter could be implemented suitably for installation or integration within the electric meter housing as an original equipment option.
The disclosed preferred embodiment also provides for error correction should a pulse count transmission be lost or corrupted. Additionally, the preferred embodiment provides relay repeating for the end-of-interval pulse so that the energy management system may synchronize its data collection and operation to the measurements from the meter, just as if they were directly connected through traditional wiring means.
In contrast to available AMR technology, the invention uses a wireless means that remains local to the customer""s premises and which is not part of a larger wireless network. Further, the meter pulse data is not concentrated with other meter data into proprietary usage data records, but are accurately repeated at the remote receiver so as to be useful and compatible with a consumer""s energy management system. Thus, the data remains within the possession of the consumer, and the usage data is not input to a utility-owned billing system but rather to an energy management system owned by the consumer.